Objectives: 1) The overall objectives of this research project are an analysis of the apoprotein composition of both rat and human mesenteric lymph chylomicrons and to investigate the structural and functional importance of these components in chylomicron formation and lipid transport. The methods of approach entail biochemical and immunologic analysis of human and rat chylomicrons coupled with studies of chylomicron formation normally and during experimental conditions of impaired lipid absorption. 2) Current goals: The goals which were set for the current year included: a) Extension of studies of lymph chylomicron composition to chylomicrons isolated from serum during alimentary lipemia in man. The purpose of these studies is to compare chylomicrons recently derived from the intestine and newly entering the circulation, with data we have obtained on human mesenteric lymph lipoproteins. b) Continuation of studies designed to locate, ultrastructurally, chylomicron apoproteins on isolated chylomicrons and within human intestinal tissue. c) Quantitative and qualitative determinaton of the glycolipid content of human and rat chylomicrons and whether these carbohydrate containing lipids are synthesized de novo by the intestine during chylomicron formation. Research accomplishments during the past year: 1) Apoprotein composition of human serum chylomicrons. In collaboration with Dr. Robert Lees, we have successfully extended our studies of human mesenteric chylomicrons to human serum chylomicrons harvested during alimentary lipemia in man. We have measured the apo B content of human serum chylomicrons by a sensitve double antibody radioimmunoassay. Various chylomicron size fractions were prepared by differential ultracentrifugation and their apo B content determined. As particle size increases higher triglyceride), there is a linear increase in apo B content. Furthermore the relative apo B content increases as a percentage of total chylomicron protein as particle size increases.